dictyNews Electronic Edition Volume 34, number 15 May 22, 2010 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to dicty@northwestern.edu or by using the form at http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit. Back issues of dictyNews, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. Follow dictyBase on twitter: http://twitter.com/dictybase ========= Abstracts ========= The glycopeptidome of a heavily N-glycosylated cell surface glycoprotein of Dictyostelium implicated in cell adhesion Christa L. Feasley, Jennifer M. Johnson, Christopher M. West, and Catherine P. Chia Department of Biochemistry & Molecular Biology and the Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104 USA; School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588-0118 USA J. Proteome Res., in press Genetic analysis has implicated the cell surface glycoprotein gp130 in cell interactions of the social amoeba Dictyostelium, and information about the utilization of the 18 N-glycosylation sequons present in gp130 is needed to identify critical molecular determinants of its activity. Various glycomics strategies, including mass spectrometry of native and derivatized glycans, monosaccharide analysis, exoglycosidase digestion and antibody binding, were applied to characterize a non-anchored version secreted from Dictyostelium. s-gp130 is modified by a predominant Man8GlcNAc4 species containing bisecting and intersecting GlcNAc residues, and additional high-mannose N-glycans substituted with sulfate, methyl-phosphate and/or core alpha3-fucose. Site mapping confirmed the occupancy of 15 sequons, some variably, and glycopeptide analysis confirmed 14 sites and revealed extensive heterogeneity at most sites. Glycopeptide glycoforms ranged from Man6 to Man9, GlcNAc0-2 (peripheral), Fuc0-2 (including core alpha3 and peripheral), (SO4)0-1, and (MePO4)0-1, which represented elements of virtually the entire known cellular N-glycome as inferred from prior metabolic labeling and mass spectrometry studies. gp130, and a family of 14 related predicted glycoproteins whose polypeptide sequences are rapidly diverging in the Dictyostelium lineage, may contribute a functionally important shroud of high-mannose N-glycans at the interface of the amoebae with each other, their predators and prey, and the soil environment. Submitted by Chris West [Cwest2@ouhsc.edu] -------------------------------------------------------------------------------- TWO NOVEL SH2 DOMAIN PROTEINS INTERACT TO REGULATE DICTYOSTELIUM GENE EXPRESSION DURING GROWTH AND EARLY DEVELOPMENT Christopher Sugden1, Susan Ross1, Gareth Bloomfield2, AlasdairIvens3, JasonSkelton3,Annette Mueller-Taubenberger4 and Jeffrey G. Williams1 School of Life Sciences1,Universityof Dundee, Dow St., Dundee DD1 5EH, UK Wellcome Trust Sanger Institute2, Hinxton, UK MRC Laboratory of Molecular Biology3, Hills Road, Cambridge, CB2 2QH, UK Institute for Cell Biology and Center for Integrated Protein Science4, Munich (CIPSM), Ludwig Maximilians University, Schillerstrasse 42, D-80336 Munich, Germany JBC, in press There are 13 Dictyostelium SH2 domain proteins, almost ten fold fewer than in mammals, and only three are functionally unassigned. One of these, LrrB, contains a novel combination of protein interaction domains: an SH2 domain and a leucine-rich repeat domain. Growth and early development appear normal in the mutant but expressionprofiling reveals that three genes active at these stages are greatly under-expressed: the ttdA metallo-hydrolase, the abcG10 small molecule transporter and the cinB esterase. In contrast, the multi-gene family encoding the lectin Discoidin 1 is over-expressed in the disruptant strain. LrrB binds to 14-3-3 protein and the level of binding is highest during growth and decreases during early development. Comparative TAP tagging shows that LrrB also interacts, via its SH2 domain and in a tyrosine phosphorylation dependent manner, with two novel proteins: CldA and CldB. Both these proteins contain a Clu domain; a >200 amino acid sequence present within highly conserved eukaryotic proteins required for correct mitochondrial dispersal. A functional interaction of LrrB with CldA is supported by the fact that a cldA disruptant mutant also under-expresses ttdA, abcG10 and cinB. Significantly, CldA is itself one of the three functionally unassigned SH2 domain proteins. Thus, just as in metazoa, but on a vastly reduced numerical scale, an interacting network of SH2 domain proteins regulates specific Dictyostelium gene expression. Submitted by Jeff Williams [j.g.williams@dundee.ac.uk] -------------------------------------------------------------------------------- Two species of dictyostelid cellular slime molds from Alaska Maria Romeralo, John C. Landolt, James C. Cavender, Gary A. Laursen, and Sandie L. Baldauf. Mycologia 2010;102 588-595. In sampling soils to survey dictyostelid cellular slime molds in Alaska we encountered two groups of isolates that have morphologies that differ from any previously described species within their group. We sequenced the nuclear small subunit ribosomal RNA gene (SSU rDNA) of selected isolates from the two groups and found sequences from both groups to be distinct from all previously described dictyostelid sequences. Phylogenetic analyses place one novel species in dictyostelid Group 2 and the other in Group 4 (Schaap et al. 2006). In this paper we formally describe as new these two species of cellular slime molds, Dictyostelium ammophilum sp. nov. and Dictyostelium boreale sp. nov., based on the combination of morphological and molecular characters. Submitted by Maria Romeralo [maria.romeralo@gmail.com] --------------------------------------------------------------------------------